INDEX. 



IX 



Quartz Rock, intrusive charficter of, 49 ; 

 microscopic study of, from Lake Superior 



Mine, 49. 

 Quartz, Veinstone, micvoscox>ic examination 

 of, 5 1 ; fluid cavities with moving bubbles, 



51. 



Quartzite, of Brooks, at Republic Mountain, 



34, 35 ; of Carp River, 9 ; defined by 

 ZIrkel, Lasaulx, and Hawes, 58 ; eruptive 

 form of, 34, 35 ; eruptive origin of, 11 ; 

 formed of detritus of jasper and iron ore, 

 59 ; granite intrusive in, 55 ; Huronian 

 R^e of, 22 ; an indurated sandstone, 58, 

 59 ; microscopic study of iron ore intru- 

 sive in, 33 ; microscopic study of, from 

 Ishpeming, 59 ; microscopic study of, 

 from Jackson Mine, 59, fiO ; microscopic 

 study of, from New York Mine, 59 ; mi- 

 croscopic study of Brooks's, from Repub- 

 lic Mountain, 54 ; of tbc New York Miuc, 

 30 ; origin of, 9 ; overlying ore, and con- 

 taining fragments of it, 33 ; ripple-marks 



in, 9, 25. 



Quebec Group, Lake Superior sandstone be- 

 longing to, 93. 



Qnincy Mine, working on an old lava How, 

 135 ; character of ore deposit, 129. 



Rainduop impressions in shale, 131. 

 Republic Mountain, diorite of, 45, 47, 49 ; 

 granite of, 52-55 ; greiscn of, 44, 5o ; 



maiinciic silicious schist of, 47 ; ore and 

 rocks of, 34 ; " qnarUite ''of, 34, 35. 

 Rhyolites, felsites oj'iginally identical with, 



38, 39, 118, 119. 

 Kliodochrosite, at McOombor Mine, 51. 



Ripple-marks, 9, 35, 79, 121. 



Rivot, L. E., his ideas iu regard to Lake 



Superior geology, 11, 12, 91. 

 Rominger, C, on the conformability of 

 Laurentian and Mui'onian, 25; dikes near 

 Marquette, 36 ; on the geological age of 

 the Kastern sandstone, 133 ; on occurrence 

 of " soft hematite," 50 ; on the Ontonagon 

 district, 104, 105 ; on i'resquo Isle serpen- 

 tine,03 ; on the relation oCthe copper-bear- 

 ing rocks to the sandstone, 103, 104; on 

 the relation of the sandstone and quartzite, 



23, 23. 

 Rocks, all suhj(M't to nlteratiou, 38, 34 ; 

 alteration accompanied by recrystallization, 

 34 ; aUcration of, a passage from an un- 

 stable condition towards a more stable one, 

 125 ; association of, 28 ; banding of, no 

 proof of stratilication, 72 ; basic eruptive, 

 of iron region, varieties of, 4G ; causes 

 of induration of, 125; determination of 

 age of, by Uthological characters, 94 ; ge- 

 ological age, told microscopically, 73, 74 ; 



their history, 28 ; intrusive garnet-bear- 

 ing actinolite probably altered andesites 

 and basalts, 49 ; intrusive, of iron district, 

 70 ; the microscopic study of, 73, 74 ; 

 mode of determining origin of, 68 ; names 

 given to local modihcatlons of, 55 ; origi- 

 nal characters of, lost, 34 ; passage of dif- 

 ferent forms into one another, 40, 09 ; 

 requirements for study of altered forms, 

 ' 74 ; resemblance does not prove identity, 

 37, 28 ; sedimentary origin of eruptive, 

 11, 12 ; superficial study of, 69. 



Rocks, crystalline, origin of, 14, 15 ; passage 

 of din'erent forms into one another, 4, 5, 

 14, 27, 37, 09 ; prc-Palseozoie age of, 5. 



Rocks, eruptive, cryGtallization of, 72; of 

 iron district, originally basalts, 46. 



Rock structures, origin of, 28. 



Rogers, H. D., copper -bearing rocks semi- 

 fused materials, 83 ; on the copper de- 

 posits, 83, 83 ; crystalline rocks of Choc- 

 olate and Carp Rivers of Primal or Pots- 

 dam age, 4 ; New Red age of Keweenaw 

 I'oint sandstone, 83. 



Rogers, W. B., Potsdam age of sandstone, 



93. 

 Rottermund, Count dc, report of, 91, 93. 

 Rugillcs, D., ou the origin of copper veins, 



SO. 



St. Maey's River, sandstone of, 77- 



.Salisbury Mine, geologiciil structure of, 50 ; 

 " soft hematite " of, 49, 50, 



Salt cubes, in granite, 25 ; in quartz, char- 

 acteristic of Iluroniau granite, 5G. 



Sand, concretions of, in shale, 131. 



Sandstone, action of trap on, 82; composed 

 of traehytie and rbyolitic material, 114, 

 115, 117, 119, 130; contact with quartz- 

 ite, 33, 23 ; containing trappean detritus, 

 110, 111; curved stratification of, 63; 

 formed of granite detritus, 60; formed 

 from volcanic dedris, 117, 118; impreg- 

 nated with iron ore, 32 ; microscopic 

 study of indurated, 114, 115; origin of, 

 122, 128 ; precipilation of copper in, by 

 organic matter, 94, 95, 109 ; pebbles of 

 qnnrt/.itc in, 113; its relation to Prosque 

 Isle peridotite, 63, 64; its relation to the 

 traps, 109-113, 118; ripple-marks in, 

 79; stalactites of, 118; thermal water 

 action on, G3, 117 ; Torch Lake quarry 

 of, 117 ; on western side of copper-bear- 

 ing rocks, 120, 131, 122; microscopic 

 Hlndy of fcldspathic, 60. 



Sandslone, Eastern, dip of, 113-119; geo- 

 logical age of, 122 ; relation to trnps, 

 108 ; younger than the copper-bearing 

 rocks, 98, 99. 



